Refrigerator drip disposal



Nov. 11, 1952 c, ASHBY E-rAL 2,617,268

REFRIGERATOR DRIP DISPOSAL Patented Nov. 11, 1952 UNITED STATES PATENT OFFICE REFRIGERATOR DRIP DISPOSAL Application July 8, 1950, Serial No. 172,67 6

1 Claim.

This invention relates to the insulating structure of refrigerators and particularly a structure for handling moisture without deterioration of the insulation.

It is theoretically possible to completely seal the insulation space around a refrigerator compartment against infiltration of Water vapor, but in practice it is complicated and expensive, and a leak is very difficult to locate. A simpler alternative is to space the insulation from the cornpartment in such manner that water vapor in the insulation is free to migrate to the compartment wall, and provide drainage for drip from the wall in a path segregated from the insulation. This requires a drain tray in the space between the insulation and the bottom of the compartment and this tray presents a considerable problem which is greater as the temperature of the refrigerator compartment is lower, becoming serious in the case of freezing compartments.

The insulation at the sides and above the cold compartment can be open for migration of water vapor, but the insulation beneath the compartment is partially shielded by the drip tray. To insure against frosting on the underside of the drip tray it must be at a much higher temperature than the cold compartment. This cannot be accomplished merely by spacing of the drip tray because increase in spacing promotes convection transfer of cold to the tray which defeats the purpose. We have found that a plurality of shallow spaces below the compartment is effective to insure against frosting on the insulation side of the drip tray. This discovery has been carried out in practice by a drip tray having several spaced layers with common drainage from all. This multilayer drain tray has proved successful, whereas the known single layer tray sweats or frosts on the bottom and impairs the insulating quality of the insulation.

The drawings herewith show more or less schematically the upper part of a household refrigerator embodying a double layer tray, Fig. 1 being a vertical section on line ii of Fig. 2, and Fig. 2 being a vertical section on line 22 of Fig. 1.

The refrigerator Ill has a sheet metal shell l2, an upper metallic liner l4. forming an open front freezing compartment I6, a lower metallic liner l8 forming an open front food storage compartment 20, and thermal insulating material 22 between the liners and the outer shell. A door, not shown, is provided for closing the front of the refrigerator, and an inner door 24, hinged at its bottom, is provided for closing the front of the freezing compartment Hi. If separate refrigera- 2 tor doors are provided for closing the compartments i6 and I8, the inner door 24 is omitted.

The upper liner M has a front edge flange 26 across the top and down both sides. A molding or breaker strip 28 formed of a suitable thermal resistant material outlines the front of the freezing compartment at the top and sides. A-pliable rubber gasket 36 seals between the flange 26 of the liner l4 and the molding 28. A gasket 32 is fitted on the bottom front edge of the liner I4 and seals between the liner and a sill 34 which has drain openings 36.

The freezing compartment i6 is cooled by a suitable low-temperature refrigerant coil 38 that is located in good thermal contact with the outer bottom surface of the liner Hi.

A housing 40 forms an open space A between the liner i l and the insulation 22 at the top, sides and rear of the freezing compartment. This housing 49 is constructed of some thermal resistant material such as chip board, for example. As a structural aid in maintaining the housing til, spacers, not shown, but constructed of thermal and water resistant material may be located between the liner i l and the housing 49. Openings A2 are provided in the top, side and rear walls of the housing 41). The many openings 42 in the housing 48 permit water vapor that may be present in the insulation 22 to migrate into the space A where it condenses and freezes on the liner M and the refrigerant coil 38. These openings are frequent enough and large enough to permit watervapor diffusion and still prevent the insulation 22 from encroaching upon and entering the space A. The air space A at the top, sides and rear of the liner I l affords room for a nonharmful frost-build-up on the outside of the liner which can then be defrosted without wetting the insulation 22.

A drip pan M, constructed of a water resistant and thermal resistant material, such as waxed chip board, is located beneath the liner I4 and affords an air space B below the bottom of the liner l4 and the attached refrigerant coil 38. Convection currents within the space B are limited and a temperature gradient exists between the refrigerant coil 38 and the drip pan 44.

The drip pan it includes two pans 46 and 48 with a space C therebetween. The space C is shallow and dampens convection currents so that another temperature gradient is established and the undersurface of the pan 48 is warm enough to avoid any condensation thereon.

The pans 46 and 48 have peripheral flanges so fitted together as to seal the space C, and secured together in any suitable manner, as by cementing, stapling, a press fit, or the like. The pans 46 and 48 each slope downward from all sides to their respective drain spouts 45a and 48a. The drain spouts are concentric and spaced to provide a passage D therebetween. The drain spout 48a fits into and is supported by a funnel 58 which projects through the top of the liner l3 and opens into the food storage compartment 29. The front edge of the drip pan 44 is supported by a ledge 52 on a molding 54 which is located across the front of the cabinet between the high and low temperature compartments. The sides of the housing 40 are supported in the pan M, and the rear Wall of the housing laps the rear edge of the drain pan.

The food storage compartment 20, formed by the lower liner I8, is cooled by a refrigerant coil 56 provided with heat transfer fins 58. The refrigerant coil 55, which operates at temperatures generally above 32 F., has an inlet conduit 60 and an outlet conduit 52 for connection to the refrigerating apparatus, not shown. A drip collecting tray 54 is located beneath the coils and fins of the evaporator section 55. A channel 66, inclined toward an opening 68 therein, is provided in the central portion of the tray 64. An extension 84a at one side of the tray 64 collects moisture that drips from the conduits 65 and 62. The tray 64 is otherwise spaced from the rear wall of the liner 18 for flow of air over the evaporator 55 and downward at the rear of the food storage compartment. A drip receiver, not shown, may be supported in any suitable manner below the opening 58 in the drip tray, or if desired, a suitable conduit may be connected to the drip tray at the opening 68 for conveying water of condensation from the tray to the exterior of the refrigerator.

To minimize movement of water vapor into the insulation 22, and the subsequent deposition of frost and water of condensation on the several surfaces that are at lower temperatures than the dew point of the atmosphere within the insulation spaces, the outer shell i2 is made as vapor tight and as completely sealed at all necessary joints as is economically feasible.

The low-temperature refrigerant coil operates at temperatures well below the freezing point of water, wherefore the partial pressure of water vapor in the space B is particularly low as compared with the partial pressure of water vapor in the insulation 22. Also, the partial pressure of water vapor in the space A around the lowtemperature compartment [6 is much lower than the partial pressure of water vapor in the insulation 22. Therefore, water vapor migrates into the space A and B from the insulation and is deposited as frost on the outer surface of the liner I4 and on the low-temperature refrigerating coil 38.

The frost that accumulates on the outer surface of the liner I4 and upon the surface of the low-temperature coil 38 must be removed from time to time. In defrosting the low-temperature coil and the low-temperature compartment, frost on the ouside of the liner I4 as well as that on the low-temperature coil 38 melts and drips onto the upper portion 46 of the drip pan 44 and flows from there through the drain spout 46a and through the funnel 50 into the high-temperature or food storage compartment 20 and is collected by the tray 64. Also, any frost that may accumulate on the undersurface of pan 45 melts and drips onto pan 48 and drains therefrom through the spout 48a and the funnel 50 into the high-temperature compartment. Moisture on the front of the low-temperature compartment and on the door 24 is caught by the sill 34 and drained through the openings 36 therein onto the drip pan ":6. Also, a drain opening, not shown, may be provided in the bottom of the liner 14 directly above the drain spout 46a for draining defrost water from the inside of the low-temperature compartment [6. In this manner substantially all moisture is removed from the low-temperature section of the refrigerator without wetting any of the insulation 22.

The refrigerant coil 58 that cools the food storage compartment 20 operates at temperatures generally above 32 F., wherefore there is little or no frost deposit upon this coil or upon the fins 58. However, there is some condensate formed upon this coil and upon the fins, and it drips into the tray 64 and drains through the channel 66 and opening 68 therein either into a suitable collecting receiver, or a suitable conduit to the outside of the refrigerator.

We claim:

A refrigerator having a compartment recessed in thermal insulation with a space between the insulation and the walls of the compartment, means for refrigerating the compartment, and a multi-layer drip tray in the space beneath the compartment with a drain from all layers of the tray projecting through the insulation.

CARL T. ASHBY. WALTER A, KUENZLI. CHARLES A. MILLER.

CES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,509,610 Philipp May 10, 1950 2,515,212 Giffard July 18, 1950 2,515,892 Philipp July 18, 1950 

